THE OLD WORLD MONKEYS
In some species it is uniformly thick, but in others it is increased in certain parts ; thus it forms a mane in the old male Gelada Baboon, and it forms a beard in Cercopithecus barbatus. In the G-uerezas there is a mantle of long hairs on the back and shoulders.
FIG. 10.—The Drill (Mandrillus leucopheeus),
The skin is dark in colour on the body, but it is frequently highly coloured on the face and buttocks. Bright pigmentation in these regions is most marked in the Mandrill and some Cercopitheques. The colour on the buttocks becomes very marked in the female at the
menstrual periods. 4